1. Technical Field
The invention relates to vacuum cleaners. Particularly, the invention relates to a dirt conveying duct arrangement for vacuum cleaners. More particularly, the invention relates to a dirt conveying duct having a front duct section open at the bottom thereof and covered by a removable bottom plate, and a rear duct section open at the top thereof and covered by a removable top duct cover.
2. Background Information
Dirt clogging of vacuum cleaners has long been a problem in the floor care art. Dirt-laden air is loosened from the floor by a cylindrical agitator and is drawn into a dirt conveying duct by a suction force produced by a motor-fan. The dirt-laden air travels through the dirt conveying duct into a motor-fan inlet of the motor-fan and is blown into a filter bag which filters the small dirt particles from the airflow. The exhaust air from the filter bag is emitted into the atmosphere. Although a clog may occur anywhere between the suction nozzle mouth and to and within the bag itself, typically these clogs occur in the dirt conveying duct between the agitator chamber and the motor-fan inlet.
Conventional vacuum cleaners include dirt conveying ducts formed with an open bottom. The open bottom is covered by the removable bottom plate which also covers the agitator chamber and belt compartment. One problem with the dirt conveying ducts of conventional vacuum cleaners is that the duct extends transversely along the foot of the vacuum cleaner while the motor-fan and agitator chamber extend longitudinally across the foot of the vacuum cleaner. Thus, the dirt-laden air drawn into the nozzle and dirt conveying duct must turn at a 90 degree angle into the motor-fan inlet where it is then blown into the filter bag. It is well known in the art of airflow that a 90 degree corner causes losses in the suction pressure and reduces the airflow velocity, thus reducing the efficiency of the vacuum cleaner.
By forming the rear of the duct with an open top, the corner between the dirt conveying duct and the motor-fan inlet may be radiused or curved to improve airflow between the duct and the motor-fan, thus increasing the suction pressure, airflow velocity and overall efficiency of the vacuum cleaner. A front duct section is open at the bottom thereof allowing for easy removal of clogs in the front of the dirt conveying duct arrangement. By forming the front of the duct with an open bottom, clogs which may occur in the front duct section may be easily accessed by removal of the bottom plate preventing time consuming disassembly of the hood and top duct cover. Further, the open front duct section provides visibility to the rear duct section allowing the user to check the rear duct section for clogs before disassembling the hood and top duct cover to gain access to the rear duct section.
Several vacuum cleaners mold the base in such a manner that corner of the duct adjacent the motor fan inlet may be radiused. For example, U.S. Pat. No. 5,383,252 discloses a suction channel molded in the nozzle and formed by integral bottom and side walls. The suction channel has an open top end which allows the motor-fan inlet to be formed with a radiused edge. A top panel is permanently attached to the upper surface of the side walls by ultrasonic welding or other equivalent process. However, after the top panel has been ultrasonically welded over the top of the duct, the user cannot easily access clogs which may occur at the rear of the dirt conveying duct.
U.S. Pat. No. 4,384,385 discloses a duct having an open top portion along the entire length of the duct and covered by a duct cap which is removably secured over the open top. A circular opening is formed in the side walls of the duct opposite the motor-fan inlet and provides access to the duct for removal of the dirt or debris retained therein. A removable stopper cap covers the dirt removal opening of the duct during operation of the vacuum cleaner.
Several other patents disclose dirt conveying ducts which allow provide for easy removal clogs. For example, U.S. Pat. No. 4,219,900 discloses a pivoting nozzle duct which is pivotally connected to the motor-fan inlet. The duct is a generally L-shaped tubular member which provides fluid communication between the agitator chamber and the motor-fan. The duct pivots out of the housing providing access thereto for de-clogging and cleaning thereof.
U.K. Patent Application GB 2043432-A discloses an air duct formed with a neck having an open front end which communicates with the agitator chamber, an enlarged rear chamber which provides communication between the neck and the motor-fan inlet and a bottom well. The bottom well is formed below the enlarged rear chamber and allows heavier objects which are picked up by the vacuum cleaner to fall therein, preventing these heavier objects from being sucked into the motor-fan inlet possibly damaging the fan blade. A hole is formed in the bottom wall of the cleaner foot for removing the heavy objects contained within the well.
Although these devices are adequate for the purposes for which they are intended, they do not disclose a two section dirt conveying duct which allows the corner between the rear duct section and the motor fan inlet to be radiused and which provides an open bottom for easy removal of clogs therefrom while providing visibility to the rear duct section allowing for the inspection of clogs therein.
Therefore, the need exists for a dirt conveying duct arrangement which has a front duct section open at the bottom thereof which allows for removal of clogs therein and which provides visibility to the rear duct section, and in which the rear duct section is open at the top thereof which allows a radiused corner to be formed between the duct and the motor-fan.